Ever increasing numbers of wireless devices are being introduced and sold. As such, the radio frequency (RF) spectrum available for these wireless devices to communicate continues to get more and more crowded. More efficient use of the RF spectrum, and sharing underutilized RF spectrum are very important to meet the growing number of wireless devices. One portion of the RF spectrum that is underutilized is the portion reserved for broadcasting television and/or radio. Governmental regulators divided the TV portion (and/or other portions) into a plurality of channels or frequencies. However, for any given geographic region many of the frequencies are not utilized for TV or radio broadcasting.
Unused frequencies of the reserved portion of the RF spectrum can be referred to as white space. It is possible to utilize these white spaces for other uses; however, their use tends to be tightly regulated by governmental institutions (such as the Federal Communications Commission in the United States).
Techniques have been attempted where a device that wants to utilize a white space frequency senses whether the white space frequency is being utilized. The device can utilize the white space frequency if the sensing indicates the white space frequency is not being utilized for other purposes. These techniques produced too many scenarios where the device's sensing missed detecting the use and its own RF transmission then created interference. When more stringent criteria are applied to avoid such situations, the devices tend to produce so many false positives that again the system is unworkable (e.g., white spaces are identified as being unavailable).
As such, the above-mentioned governmental institutions decided to establish regulatory databases that map channel or frequency utilization to geographic location. Stated another way, for a given geographic location, the database indicates a sub-set of frequencies or channels that are utilized for broadcasting and other licensed use (such as wireless microphones in some countries) and/or a different sub-set of frequencies that are white spaces. Potentially, the governmental institutions may allow individual white space frequencies to be temporarily used for other purposes. However, any access point device (sometimes referred to as a “master”) that wants to temporarily use one or more of these white space frequencies has to have the capability to know its own geographic location to within an accuracy acceptable by the regulators and also has to have access to the database via the Internet so that the device's location can be utilized in conjunction with the locations in the database. The device may be able to obtain authorization to utilize individual white space frequencies according to specific conditions or constraints. For instance, the constraints may relate to the location of the device, a duration of the authorization, and/or an allowed transmission power. Other available radio frequencies may be handled in a similar manner. The regulatory database system imposes a high overhead on devices trying to use white spaces (e.g., the ability to access the database and the ability to self-determine geographic location). Further, the regulatory databases tend to be set up very conservatively to avoid interfering uses and, as such, available white spaces remain unused.